/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.db.mpp.execution.operator.schema;

import com.google.common.util.concurrent.ListenableFuture;
import org.apache.iotdb.db.mpp.execution.operator.Operator;
import org.apache.iotdb.db.mpp.execution.operator.OperatorContext;
import org.apache.iotdb.db.mpp.execution.operator.process.ProcessOperator;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanNodeId;
import org.apache.iotdb.tsfile.read.common.block.TsBlock;

import java.util.List;

public class SchemaQueryMergeOperator implements ProcessOperator {
    private final PlanNodeId planNodeId;
    private final OperatorContext operatorContext;

    private final List<Operator> children;

    private int currentIndex;

    public SchemaQueryMergeOperator(
            PlanNodeId planNodeId, OperatorContext operatorContext, List<Operator> children) {
        this.planNodeId = planNodeId;
        this.operatorContext = operatorContext;
        this.children = children;
        this.currentIndex = 0;
    }

    @Override
    public OperatorContext getOperatorContext() {
        return operatorContext;
    }

    @Override
    public TsBlock next() {
        if (children.get(currentIndex).hasNextWithTimer()) {
            return children.get(currentIndex).nextWithTimer();
        } else {
            currentIndex++;
            return null;
        }
    }

    @Override
    public boolean hasNext() {
        return currentIndex < children.size();
    }

    @Override
    public ListenableFuture<?> isBlocked() {
        return currentIndex < children.size() ? children.get(currentIndex).isBlocked() : NOT_BLOCKED;
    }

    @Override
    public boolean isFinished() {
        return !hasNextWithTimer();
    }

    @Override
    public void close() throws Exception {
        for (Operator child : children) {
            child.close();
        }
    }

    @Override
    public long calculateMaxPeekMemory() {
        long childrenMaxPeekMemory = 0;
        for (Operator child : children) {
            childrenMaxPeekMemory = Math.max(childrenMaxPeekMemory, child.calculateMaxPeekMemory());
        }

        return childrenMaxPeekMemory;
    }

    @Override
    public long calculateMaxReturnSize() {
        long childrenMaxReturnSize = 0;
        for (Operator child : children) {
            childrenMaxReturnSize = Math.max(childrenMaxReturnSize, child.calculateMaxReturnSize());
        }

        return childrenMaxReturnSize;
    }

    @Override
    public long calculateRetainedSizeAfterCallingNext() {
        long retainedSize = 0L;
        for (Operator child : children) {
            retainedSize += child.calculateRetainedSizeAfterCallingNext();
        }
        return retainedSize;
    }
}
